xref: /openbmc/linux/kernel/fork.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  *  linux/kernel/fork.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6 
7 /*
8  *  'fork.c' contains the help-routines for the 'fork' system call
9  * (see also entry.S and others).
10  * Fork is rather simple, once you get the hang of it, but the memory
11  * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
12  */
13 
14 #include <linux/config.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/unistd.h>
18 #include <linux/smp_lock.h>
19 #include <linux/module.h>
20 #include <linux/vmalloc.h>
21 #include <linux/completion.h>
22 #include <linux/namespace.h>
23 #include <linux/personality.h>
24 #include <linux/mempolicy.h>
25 #include <linux/sem.h>
26 #include <linux/file.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.h>
30 #include <linux/fs.h>
31 #include <linux/cpu.h>
32 #include <linux/cpuset.h>
33 #include <linux/security.h>
34 #include <linux/swap.h>
35 #include <linux/syscalls.h>
36 #include <linux/jiffies.h>
37 #include <linux/futex.h>
38 #include <linux/rcupdate.h>
39 #include <linux/ptrace.h>
40 #include <linux/mount.h>
41 #include <linux/audit.h>
42 #include <linux/profile.h>
43 #include <linux/rmap.h>
44 #include <linux/acct.h>
45 
46 #include <asm/pgtable.h>
47 #include <asm/pgalloc.h>
48 #include <asm/uaccess.h>
49 #include <asm/mmu_context.h>
50 #include <asm/cacheflush.h>
51 #include <asm/tlbflush.h>
52 
53 /*
54  * Protected counters by write_lock_irq(&tasklist_lock)
55  */
56 unsigned long total_forks;	/* Handle normal Linux uptimes. */
57 int nr_threads; 		/* The idle threads do not count.. */
58 
59 int max_threads;		/* tunable limit on nr_threads */
60 
61 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
62 
63  __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
64 
65 EXPORT_SYMBOL(tasklist_lock);
66 
67 int nr_processes(void)
68 {
69 	int cpu;
70 	int total = 0;
71 
72 	for_each_online_cpu(cpu)
73 		total += per_cpu(process_counts, cpu);
74 
75 	return total;
76 }
77 
78 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
79 # define alloc_task_struct()	kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
80 # define free_task_struct(tsk)	kmem_cache_free(task_struct_cachep, (tsk))
81 static kmem_cache_t *task_struct_cachep;
82 #endif
83 
84 /* SLAB cache for signal_struct structures (tsk->signal) */
85 kmem_cache_t *signal_cachep;
86 
87 /* SLAB cache for sighand_struct structures (tsk->sighand) */
88 kmem_cache_t *sighand_cachep;
89 
90 /* SLAB cache for files_struct structures (tsk->files) */
91 kmem_cache_t *files_cachep;
92 
93 /* SLAB cache for fs_struct structures (tsk->fs) */
94 kmem_cache_t *fs_cachep;
95 
96 /* SLAB cache for vm_area_struct structures */
97 kmem_cache_t *vm_area_cachep;
98 
99 /* SLAB cache for mm_struct structures (tsk->mm) */
100 static kmem_cache_t *mm_cachep;
101 
102 void free_task(struct task_struct *tsk)
103 {
104 	free_thread_info(tsk->thread_info);
105 	free_task_struct(tsk);
106 }
107 EXPORT_SYMBOL(free_task);
108 
109 void __put_task_struct(struct task_struct *tsk)
110 {
111 	WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
112 	WARN_ON(atomic_read(&tsk->usage));
113 	WARN_ON(tsk == current);
114 
115 	if (unlikely(tsk->audit_context))
116 		audit_free(tsk);
117 	security_task_free(tsk);
118 	free_uid(tsk->user);
119 	put_group_info(tsk->group_info);
120 
121 	if (!profile_handoff_task(tsk))
122 		free_task(tsk);
123 }
124 
125 void __init fork_init(unsigned long mempages)
126 {
127 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
128 #ifndef ARCH_MIN_TASKALIGN
129 #define ARCH_MIN_TASKALIGN	L1_CACHE_BYTES
130 #endif
131 	/* create a slab on which task_structs can be allocated */
132 	task_struct_cachep =
133 		kmem_cache_create("task_struct", sizeof(struct task_struct),
134 			ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
135 #endif
136 
137 	/*
138 	 * The default maximum number of threads is set to a safe
139 	 * value: the thread structures can take up at most half
140 	 * of memory.
141 	 */
142 	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
143 
144 	/*
145 	 * we need to allow at least 20 threads to boot a system
146 	 */
147 	if(max_threads < 20)
148 		max_threads = 20;
149 
150 	init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
151 	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
152 	init_task.signal->rlim[RLIMIT_SIGPENDING] =
153 		init_task.signal->rlim[RLIMIT_NPROC];
154 }
155 
156 static struct task_struct *dup_task_struct(struct task_struct *orig)
157 {
158 	struct task_struct *tsk;
159 	struct thread_info *ti;
160 
161 	prepare_to_copy(orig);
162 
163 	tsk = alloc_task_struct();
164 	if (!tsk)
165 		return NULL;
166 
167 	ti = alloc_thread_info(tsk);
168 	if (!ti) {
169 		free_task_struct(tsk);
170 		return NULL;
171 	}
172 
173 	*ti = *orig->thread_info;
174 	*tsk = *orig;
175 	tsk->thread_info = ti;
176 	ti->task = tsk;
177 
178 	/* One for us, one for whoever does the "release_task()" (usually parent) */
179 	atomic_set(&tsk->usage,2);
180 	atomic_set(&tsk->fs_excl, 0);
181 	return tsk;
182 }
183 
184 #ifdef CONFIG_MMU
185 static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
186 {
187 	struct vm_area_struct *mpnt, *tmp, **pprev;
188 	struct rb_node **rb_link, *rb_parent;
189 	int retval;
190 	unsigned long charge;
191 	struct mempolicy *pol;
192 
193 	down_write(&oldmm->mmap_sem);
194 	flush_cache_mm(oldmm);
195 	down_write(&mm->mmap_sem);
196 
197 	mm->locked_vm = 0;
198 	mm->mmap = NULL;
199 	mm->mmap_cache = NULL;
200 	mm->free_area_cache = oldmm->mmap_base;
201 	mm->cached_hole_size = ~0UL;
202 	mm->map_count = 0;
203 	cpus_clear(mm->cpu_vm_mask);
204 	mm->mm_rb = RB_ROOT;
205 	rb_link = &mm->mm_rb.rb_node;
206 	rb_parent = NULL;
207 	pprev = &mm->mmap;
208 
209 	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
210 		struct file *file;
211 
212 		if (mpnt->vm_flags & VM_DONTCOPY) {
213 			long pages = vma_pages(mpnt);
214 			mm->total_vm -= pages;
215 			vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
216 								-pages);
217 			continue;
218 		}
219 		charge = 0;
220 		if (mpnt->vm_flags & VM_ACCOUNT) {
221 			unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
222 			if (security_vm_enough_memory(len))
223 				goto fail_nomem;
224 			charge = len;
225 		}
226 		tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
227 		if (!tmp)
228 			goto fail_nomem;
229 		*tmp = *mpnt;
230 		pol = mpol_copy(vma_policy(mpnt));
231 		retval = PTR_ERR(pol);
232 		if (IS_ERR(pol))
233 			goto fail_nomem_policy;
234 		vma_set_policy(tmp, pol);
235 		tmp->vm_flags &= ~VM_LOCKED;
236 		tmp->vm_mm = mm;
237 		tmp->vm_next = NULL;
238 		anon_vma_link(tmp);
239 		file = tmp->vm_file;
240 		if (file) {
241 			struct inode *inode = file->f_dentry->d_inode;
242 			get_file(file);
243 			if (tmp->vm_flags & VM_DENYWRITE)
244 				atomic_dec(&inode->i_writecount);
245 
246 			/* insert tmp into the share list, just after mpnt */
247 			spin_lock(&file->f_mapping->i_mmap_lock);
248 			tmp->vm_truncate_count = mpnt->vm_truncate_count;
249 			flush_dcache_mmap_lock(file->f_mapping);
250 			vma_prio_tree_add(tmp, mpnt);
251 			flush_dcache_mmap_unlock(file->f_mapping);
252 			spin_unlock(&file->f_mapping->i_mmap_lock);
253 		}
254 
255 		/*
256 		 * Link in the new vma and copy the page table entries.
257 		 */
258 		*pprev = tmp;
259 		pprev = &tmp->vm_next;
260 
261 		__vma_link_rb(mm, tmp, rb_link, rb_parent);
262 		rb_link = &tmp->vm_rb.rb_right;
263 		rb_parent = &tmp->vm_rb;
264 
265 		mm->map_count++;
266 		retval = copy_page_range(mm, oldmm, tmp);
267 
268 		if (tmp->vm_ops && tmp->vm_ops->open)
269 			tmp->vm_ops->open(tmp);
270 
271 		if (retval)
272 			goto out;
273 	}
274 	retval = 0;
275 out:
276 	up_write(&mm->mmap_sem);
277 	flush_tlb_mm(oldmm);
278 	up_write(&oldmm->mmap_sem);
279 	return retval;
280 fail_nomem_policy:
281 	kmem_cache_free(vm_area_cachep, tmp);
282 fail_nomem:
283 	retval = -ENOMEM;
284 	vm_unacct_memory(charge);
285 	goto out;
286 }
287 
288 static inline int mm_alloc_pgd(struct mm_struct * mm)
289 {
290 	mm->pgd = pgd_alloc(mm);
291 	if (unlikely(!mm->pgd))
292 		return -ENOMEM;
293 	return 0;
294 }
295 
296 static inline void mm_free_pgd(struct mm_struct * mm)
297 {
298 	pgd_free(mm->pgd);
299 }
300 #else
301 #define dup_mmap(mm, oldmm)	(0)
302 #define mm_alloc_pgd(mm)	(0)
303 #define mm_free_pgd(mm)
304 #endif /* CONFIG_MMU */
305 
306  __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
307 
308 #define allocate_mm()	(kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
309 #define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))
310 
311 #include <linux/init_task.h>
312 
313 static struct mm_struct * mm_init(struct mm_struct * mm)
314 {
315 	atomic_set(&mm->mm_users, 1);
316 	atomic_set(&mm->mm_count, 1);
317 	init_rwsem(&mm->mmap_sem);
318 	INIT_LIST_HEAD(&mm->mmlist);
319 	mm->core_waiters = 0;
320 	mm->nr_ptes = 0;
321 	set_mm_counter(mm, file_rss, 0);
322 	set_mm_counter(mm, anon_rss, 0);
323 	spin_lock_init(&mm->page_table_lock);
324 	rwlock_init(&mm->ioctx_list_lock);
325 	mm->ioctx_list = NULL;
326 	mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
327 	mm->free_area_cache = TASK_UNMAPPED_BASE;
328 	mm->cached_hole_size = ~0UL;
329 
330 	if (likely(!mm_alloc_pgd(mm))) {
331 		mm->def_flags = 0;
332 		return mm;
333 	}
334 	free_mm(mm);
335 	return NULL;
336 }
337 
338 /*
339  * Allocate and initialize an mm_struct.
340  */
341 struct mm_struct * mm_alloc(void)
342 {
343 	struct mm_struct * mm;
344 
345 	mm = allocate_mm();
346 	if (mm) {
347 		memset(mm, 0, sizeof(*mm));
348 		mm = mm_init(mm);
349 	}
350 	return mm;
351 }
352 
353 /*
354  * Called when the last reference to the mm
355  * is dropped: either by a lazy thread or by
356  * mmput. Free the page directory and the mm.
357  */
358 void fastcall __mmdrop(struct mm_struct *mm)
359 {
360 	BUG_ON(mm == &init_mm);
361 	mm_free_pgd(mm);
362 	destroy_context(mm);
363 	free_mm(mm);
364 }
365 
366 /*
367  * Decrement the use count and release all resources for an mm.
368  */
369 void mmput(struct mm_struct *mm)
370 {
371 	if (atomic_dec_and_test(&mm->mm_users)) {
372 		exit_aio(mm);
373 		exit_mmap(mm);
374 		if (!list_empty(&mm->mmlist)) {
375 			spin_lock(&mmlist_lock);
376 			list_del(&mm->mmlist);
377 			spin_unlock(&mmlist_lock);
378 		}
379 		put_swap_token(mm);
380 		mmdrop(mm);
381 	}
382 }
383 EXPORT_SYMBOL_GPL(mmput);
384 
385 /**
386  * get_task_mm - acquire a reference to the task's mm
387  *
388  * Returns %NULL if the task has no mm.  Checks PF_BORROWED_MM (meaning
389  * this kernel workthread has transiently adopted a user mm with use_mm,
390  * to do its AIO) is not set and if so returns a reference to it, after
391  * bumping up the use count.  User must release the mm via mmput()
392  * after use.  Typically used by /proc and ptrace.
393  */
394 struct mm_struct *get_task_mm(struct task_struct *task)
395 {
396 	struct mm_struct *mm;
397 
398 	task_lock(task);
399 	mm = task->mm;
400 	if (mm) {
401 		if (task->flags & PF_BORROWED_MM)
402 			mm = NULL;
403 		else
404 			atomic_inc(&mm->mm_users);
405 	}
406 	task_unlock(task);
407 	return mm;
408 }
409 EXPORT_SYMBOL_GPL(get_task_mm);
410 
411 /* Please note the differences between mmput and mm_release.
412  * mmput is called whenever we stop holding onto a mm_struct,
413  * error success whatever.
414  *
415  * mm_release is called after a mm_struct has been removed
416  * from the current process.
417  *
418  * This difference is important for error handling, when we
419  * only half set up a mm_struct for a new process and need to restore
420  * the old one.  Because we mmput the new mm_struct before
421  * restoring the old one. . .
422  * Eric Biederman 10 January 1998
423  */
424 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
425 {
426 	struct completion *vfork_done = tsk->vfork_done;
427 
428 	/* Get rid of any cached register state */
429 	deactivate_mm(tsk, mm);
430 
431 	/* notify parent sleeping on vfork() */
432 	if (vfork_done) {
433 		tsk->vfork_done = NULL;
434 		complete(vfork_done);
435 	}
436 	if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
437 		u32 __user * tidptr = tsk->clear_child_tid;
438 		tsk->clear_child_tid = NULL;
439 
440 		/*
441 		 * We don't check the error code - if userspace has
442 		 * not set up a proper pointer then tough luck.
443 		 */
444 		put_user(0, tidptr);
445 		sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
446 	}
447 }
448 
449 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
450 {
451 	struct mm_struct * mm, *oldmm;
452 	int retval;
453 
454 	tsk->min_flt = tsk->maj_flt = 0;
455 	tsk->nvcsw = tsk->nivcsw = 0;
456 
457 	tsk->mm = NULL;
458 	tsk->active_mm = NULL;
459 
460 	/*
461 	 * Are we cloning a kernel thread?
462 	 *
463 	 * We need to steal a active VM for that..
464 	 */
465 	oldmm = current->mm;
466 	if (!oldmm)
467 		return 0;
468 
469 	if (clone_flags & CLONE_VM) {
470 		atomic_inc(&oldmm->mm_users);
471 		mm = oldmm;
472 		/*
473 		 * There are cases where the PTL is held to ensure no
474 		 * new threads start up in user mode using an mm, which
475 		 * allows optimizing out ipis; the tlb_gather_mmu code
476 		 * is an example.
477 		 */
478 		spin_unlock_wait(&oldmm->page_table_lock);
479 		goto good_mm;
480 	}
481 
482 	retval = -ENOMEM;
483 	mm = allocate_mm();
484 	if (!mm)
485 		goto fail_nomem;
486 
487 	/* Copy the current MM stuff.. */
488 	memcpy(mm, oldmm, sizeof(*mm));
489 	if (!mm_init(mm))
490 		goto fail_nomem;
491 
492 	if (init_new_context(tsk,mm))
493 		goto fail_nocontext;
494 
495 	retval = dup_mmap(mm, oldmm);
496 	if (retval)
497 		goto free_pt;
498 
499 	mm->hiwater_rss = get_mm_rss(mm);
500 	mm->hiwater_vm = mm->total_vm;
501 
502 good_mm:
503 	tsk->mm = mm;
504 	tsk->active_mm = mm;
505 	return 0;
506 
507 free_pt:
508 	mmput(mm);
509 fail_nomem:
510 	return retval;
511 
512 fail_nocontext:
513 	/*
514 	 * If init_new_context() failed, we cannot use mmput() to free the mm
515 	 * because it calls destroy_context()
516 	 */
517 	mm_free_pgd(mm);
518 	free_mm(mm);
519 	return retval;
520 }
521 
522 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
523 {
524 	struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
525 	/* We don't need to lock fs - think why ;-) */
526 	if (fs) {
527 		atomic_set(&fs->count, 1);
528 		rwlock_init(&fs->lock);
529 		fs->umask = old->umask;
530 		read_lock(&old->lock);
531 		fs->rootmnt = mntget(old->rootmnt);
532 		fs->root = dget(old->root);
533 		fs->pwdmnt = mntget(old->pwdmnt);
534 		fs->pwd = dget(old->pwd);
535 		if (old->altroot) {
536 			fs->altrootmnt = mntget(old->altrootmnt);
537 			fs->altroot = dget(old->altroot);
538 		} else {
539 			fs->altrootmnt = NULL;
540 			fs->altroot = NULL;
541 		}
542 		read_unlock(&old->lock);
543 	}
544 	return fs;
545 }
546 
547 struct fs_struct *copy_fs_struct(struct fs_struct *old)
548 {
549 	return __copy_fs_struct(old);
550 }
551 
552 EXPORT_SYMBOL_GPL(copy_fs_struct);
553 
554 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
555 {
556 	if (clone_flags & CLONE_FS) {
557 		atomic_inc(&current->fs->count);
558 		return 0;
559 	}
560 	tsk->fs = __copy_fs_struct(current->fs);
561 	if (!tsk->fs)
562 		return -ENOMEM;
563 	return 0;
564 }
565 
566 static int count_open_files(struct fdtable *fdt)
567 {
568 	int size = fdt->max_fdset;
569 	int i;
570 
571 	/* Find the last open fd */
572 	for (i = size/(8*sizeof(long)); i > 0; ) {
573 		if (fdt->open_fds->fds_bits[--i])
574 			break;
575 	}
576 	i = (i+1) * 8 * sizeof(long);
577 	return i;
578 }
579 
580 static struct files_struct *alloc_files(void)
581 {
582 	struct files_struct *newf;
583 	struct fdtable *fdt;
584 
585 	newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
586 	if (!newf)
587 		goto out;
588 
589 	atomic_set(&newf->count, 1);
590 
591 	spin_lock_init(&newf->file_lock);
592 	fdt = &newf->fdtab;
593 	fdt->next_fd = 0;
594 	fdt->max_fds = NR_OPEN_DEFAULT;
595 	fdt->max_fdset = __FD_SETSIZE;
596 	fdt->close_on_exec = &newf->close_on_exec_init;
597 	fdt->open_fds = &newf->open_fds_init;
598 	fdt->fd = &newf->fd_array[0];
599 	INIT_RCU_HEAD(&fdt->rcu);
600 	fdt->free_files = NULL;
601 	fdt->next = NULL;
602 	rcu_assign_pointer(newf->fdt, fdt);
603 out:
604 	return newf;
605 }
606 
607 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
608 {
609 	struct files_struct *oldf, *newf;
610 	struct file **old_fds, **new_fds;
611 	int open_files, size, i, error = 0, expand;
612 	struct fdtable *old_fdt, *new_fdt;
613 
614 	/*
615 	 * A background process may not have any files ...
616 	 */
617 	oldf = current->files;
618 	if (!oldf)
619 		goto out;
620 
621 	if (clone_flags & CLONE_FILES) {
622 		atomic_inc(&oldf->count);
623 		goto out;
624 	}
625 
626 	/*
627 	 * Note: we may be using current for both targets (See exec.c)
628 	 * This works because we cache current->files (old) as oldf. Don't
629 	 * break this.
630 	 */
631 	tsk->files = NULL;
632 	error = -ENOMEM;
633 	newf = alloc_files();
634 	if (!newf)
635 		goto out;
636 
637 	spin_lock(&oldf->file_lock);
638 	old_fdt = files_fdtable(oldf);
639 	new_fdt = files_fdtable(newf);
640 	size = old_fdt->max_fdset;
641 	open_files = count_open_files(old_fdt);
642 	expand = 0;
643 
644 	/*
645 	 * Check whether we need to allocate a larger fd array or fd set.
646 	 * Note: we're not a clone task, so the open count won't  change.
647 	 */
648 	if (open_files > new_fdt->max_fdset) {
649 		new_fdt->max_fdset = 0;
650 		expand = 1;
651 	}
652 	if (open_files > new_fdt->max_fds) {
653 		new_fdt->max_fds = 0;
654 		expand = 1;
655 	}
656 
657 	/* if the old fdset gets grown now, we'll only copy up to "size" fds */
658 	if (expand) {
659 		spin_unlock(&oldf->file_lock);
660 		spin_lock(&newf->file_lock);
661 		error = expand_files(newf, open_files-1);
662 		spin_unlock(&newf->file_lock);
663 		if (error < 0)
664 			goto out_release;
665 		new_fdt = files_fdtable(newf);
666 		/*
667 		 * Reacquire the oldf lock and a pointer to its fd table
668 		 * who knows it may have a new bigger fd table. We need
669 		 * the latest pointer.
670 		 */
671 		spin_lock(&oldf->file_lock);
672 		old_fdt = files_fdtable(oldf);
673 	}
674 
675 	old_fds = old_fdt->fd;
676 	new_fds = new_fdt->fd;
677 
678 	memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
679 	memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
680 
681 	for (i = open_files; i != 0; i--) {
682 		struct file *f = *old_fds++;
683 		if (f) {
684 			get_file(f);
685 		} else {
686 			/*
687 			 * The fd may be claimed in the fd bitmap but not yet
688 			 * instantiated in the files array if a sibling thread
689 			 * is partway through open().  So make sure that this
690 			 * fd is available to the new process.
691 			 */
692 			FD_CLR(open_files - i, new_fdt->open_fds);
693 		}
694 		rcu_assign_pointer(*new_fds++, f);
695 	}
696 	spin_unlock(&oldf->file_lock);
697 
698 	/* compute the remainder to be cleared */
699 	size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
700 
701 	/* This is long word aligned thus could use a optimized version */
702 	memset(new_fds, 0, size);
703 
704 	if (new_fdt->max_fdset > open_files) {
705 		int left = (new_fdt->max_fdset-open_files)/8;
706 		int start = open_files / (8 * sizeof(unsigned long));
707 
708 		memset(&new_fdt->open_fds->fds_bits[start], 0, left);
709 		memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
710 	}
711 
712 	tsk->files = newf;
713 	error = 0;
714 out:
715 	return error;
716 
717 out_release:
718 	free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
719 	free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
720 	free_fd_array(new_fdt->fd, new_fdt->max_fds);
721 	kmem_cache_free(files_cachep, newf);
722 	goto out;
723 }
724 
725 /*
726  *	Helper to unshare the files of the current task.
727  *	We don't want to expose copy_files internals to
728  *	the exec layer of the kernel.
729  */
730 
731 int unshare_files(void)
732 {
733 	struct files_struct *files  = current->files;
734 	int rc;
735 
736 	if(!files)
737 		BUG();
738 
739 	/* This can race but the race causes us to copy when we don't
740 	   need to and drop the copy */
741 	if(atomic_read(&files->count) == 1)
742 	{
743 		atomic_inc(&files->count);
744 		return 0;
745 	}
746 	rc = copy_files(0, current);
747 	if(rc)
748 		current->files = files;
749 	return rc;
750 }
751 
752 EXPORT_SYMBOL(unshare_files);
753 
754 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
755 {
756 	struct sighand_struct *sig;
757 
758 	if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
759 		atomic_inc(&current->sighand->count);
760 		return 0;
761 	}
762 	sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
763 	tsk->sighand = sig;
764 	if (!sig)
765 		return -ENOMEM;
766 	spin_lock_init(&sig->siglock);
767 	atomic_set(&sig->count, 1);
768 	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
769 	return 0;
770 }
771 
772 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
773 {
774 	struct signal_struct *sig;
775 	int ret;
776 
777 	if (clone_flags & CLONE_THREAD) {
778 		atomic_inc(&current->signal->count);
779 		atomic_inc(&current->signal->live);
780 		return 0;
781 	}
782 	sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
783 	tsk->signal = sig;
784 	if (!sig)
785 		return -ENOMEM;
786 
787 	ret = copy_thread_group_keys(tsk);
788 	if (ret < 0) {
789 		kmem_cache_free(signal_cachep, sig);
790 		return ret;
791 	}
792 
793 	atomic_set(&sig->count, 1);
794 	atomic_set(&sig->live, 1);
795 	init_waitqueue_head(&sig->wait_chldexit);
796 	sig->flags = 0;
797 	sig->group_exit_code = 0;
798 	sig->group_exit_task = NULL;
799 	sig->group_stop_count = 0;
800 	sig->curr_target = NULL;
801 	init_sigpending(&sig->shared_pending);
802 	INIT_LIST_HEAD(&sig->posix_timers);
803 
804 	sig->it_real_value = sig->it_real_incr = 0;
805 	sig->real_timer.function = it_real_fn;
806 	sig->real_timer.data = (unsigned long) tsk;
807 	init_timer(&sig->real_timer);
808 
809 	sig->it_virt_expires = cputime_zero;
810 	sig->it_virt_incr = cputime_zero;
811 	sig->it_prof_expires = cputime_zero;
812 	sig->it_prof_incr = cputime_zero;
813 
814 	sig->tty = current->signal->tty;
815 	sig->pgrp = process_group(current);
816 	sig->session = current->signal->session;
817 	sig->leader = 0;	/* session leadership doesn't inherit */
818 	sig->tty_old_pgrp = 0;
819 
820 	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
821 	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
822 	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
823 	sig->sched_time = 0;
824 	INIT_LIST_HEAD(&sig->cpu_timers[0]);
825 	INIT_LIST_HEAD(&sig->cpu_timers[1]);
826 	INIT_LIST_HEAD(&sig->cpu_timers[2]);
827 
828 	task_lock(current->group_leader);
829 	memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
830 	task_unlock(current->group_leader);
831 
832 	if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
833 		/*
834 		 * New sole thread in the process gets an expiry time
835 		 * of the whole CPU time limit.
836 		 */
837 		tsk->it_prof_expires =
838 			secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
839 	}
840 
841 	return 0;
842 }
843 
844 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
845 {
846 	unsigned long new_flags = p->flags;
847 
848 	new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
849 	new_flags |= PF_FORKNOEXEC;
850 	if (!(clone_flags & CLONE_PTRACE))
851 		p->ptrace = 0;
852 	p->flags = new_flags;
853 }
854 
855 asmlinkage long sys_set_tid_address(int __user *tidptr)
856 {
857 	current->clear_child_tid = tidptr;
858 
859 	return current->pid;
860 }
861 
862 /*
863  * This creates a new process as a copy of the old one,
864  * but does not actually start it yet.
865  *
866  * It copies the registers, and all the appropriate
867  * parts of the process environment (as per the clone
868  * flags). The actual kick-off is left to the caller.
869  */
870 static task_t *copy_process(unsigned long clone_flags,
871 				 unsigned long stack_start,
872 				 struct pt_regs *regs,
873 				 unsigned long stack_size,
874 				 int __user *parent_tidptr,
875 				 int __user *child_tidptr,
876 				 int pid)
877 {
878 	int retval;
879 	struct task_struct *p = NULL;
880 
881 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
882 		return ERR_PTR(-EINVAL);
883 
884 	/*
885 	 * Thread groups must share signals as well, and detached threads
886 	 * can only be started up within the thread group.
887 	 */
888 	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
889 		return ERR_PTR(-EINVAL);
890 
891 	/*
892 	 * Shared signal handlers imply shared VM. By way of the above,
893 	 * thread groups also imply shared VM. Blocking this case allows
894 	 * for various simplifications in other code.
895 	 */
896 	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
897 		return ERR_PTR(-EINVAL);
898 
899 	retval = security_task_create(clone_flags);
900 	if (retval)
901 		goto fork_out;
902 
903 	retval = -ENOMEM;
904 	p = dup_task_struct(current);
905 	if (!p)
906 		goto fork_out;
907 
908 	retval = -EAGAIN;
909 	if (atomic_read(&p->user->processes) >=
910 			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
911 		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
912 				p->user != &root_user)
913 			goto bad_fork_free;
914 	}
915 
916 	atomic_inc(&p->user->__count);
917 	atomic_inc(&p->user->processes);
918 	get_group_info(p->group_info);
919 
920 	/*
921 	 * If multiple threads are within copy_process(), then this check
922 	 * triggers too late. This doesn't hurt, the check is only there
923 	 * to stop root fork bombs.
924 	 */
925 	if (nr_threads >= max_threads)
926 		goto bad_fork_cleanup_count;
927 
928 	if (!try_module_get(p->thread_info->exec_domain->module))
929 		goto bad_fork_cleanup_count;
930 
931 	if (p->binfmt && !try_module_get(p->binfmt->module))
932 		goto bad_fork_cleanup_put_domain;
933 
934 	p->did_exec = 0;
935 	copy_flags(clone_flags, p);
936 	p->pid = pid;
937 	retval = -EFAULT;
938 	if (clone_flags & CLONE_PARENT_SETTID)
939 		if (put_user(p->pid, parent_tidptr))
940 			goto bad_fork_cleanup;
941 
942 	p->proc_dentry = NULL;
943 
944 	INIT_LIST_HEAD(&p->children);
945 	INIT_LIST_HEAD(&p->sibling);
946 	p->vfork_done = NULL;
947 	spin_lock_init(&p->alloc_lock);
948 	spin_lock_init(&p->proc_lock);
949 
950 	clear_tsk_thread_flag(p, TIF_SIGPENDING);
951 	init_sigpending(&p->pending);
952 
953 	p->utime = cputime_zero;
954 	p->stime = cputime_zero;
955  	p->sched_time = 0;
956 	p->rchar = 0;		/* I/O counter: bytes read */
957 	p->wchar = 0;		/* I/O counter: bytes written */
958 	p->syscr = 0;		/* I/O counter: read syscalls */
959 	p->syscw = 0;		/* I/O counter: write syscalls */
960 	acct_clear_integrals(p);
961 
962  	p->it_virt_expires = cputime_zero;
963 	p->it_prof_expires = cputime_zero;
964  	p->it_sched_expires = 0;
965  	INIT_LIST_HEAD(&p->cpu_timers[0]);
966  	INIT_LIST_HEAD(&p->cpu_timers[1]);
967  	INIT_LIST_HEAD(&p->cpu_timers[2]);
968 
969 	p->lock_depth = -1;		/* -1 = no lock */
970 	do_posix_clock_monotonic_gettime(&p->start_time);
971 	p->security = NULL;
972 	p->io_context = NULL;
973 	p->io_wait = NULL;
974 	p->audit_context = NULL;
975 #ifdef CONFIG_NUMA
976  	p->mempolicy = mpol_copy(p->mempolicy);
977  	if (IS_ERR(p->mempolicy)) {
978  		retval = PTR_ERR(p->mempolicy);
979  		p->mempolicy = NULL;
980  		goto bad_fork_cleanup;
981  	}
982 #endif
983 
984 	p->tgid = p->pid;
985 	if (clone_flags & CLONE_THREAD)
986 		p->tgid = current->tgid;
987 
988 	if ((retval = security_task_alloc(p)))
989 		goto bad_fork_cleanup_policy;
990 	if ((retval = audit_alloc(p)))
991 		goto bad_fork_cleanup_security;
992 	/* copy all the process information */
993 	if ((retval = copy_semundo(clone_flags, p)))
994 		goto bad_fork_cleanup_audit;
995 	if ((retval = copy_files(clone_flags, p)))
996 		goto bad_fork_cleanup_semundo;
997 	if ((retval = copy_fs(clone_flags, p)))
998 		goto bad_fork_cleanup_files;
999 	if ((retval = copy_sighand(clone_flags, p)))
1000 		goto bad_fork_cleanup_fs;
1001 	if ((retval = copy_signal(clone_flags, p)))
1002 		goto bad_fork_cleanup_sighand;
1003 	if ((retval = copy_mm(clone_flags, p)))
1004 		goto bad_fork_cleanup_signal;
1005 	if ((retval = copy_keys(clone_flags, p)))
1006 		goto bad_fork_cleanup_mm;
1007 	if ((retval = copy_namespace(clone_flags, p)))
1008 		goto bad_fork_cleanup_keys;
1009 	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1010 	if (retval)
1011 		goto bad_fork_cleanup_namespace;
1012 
1013 	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1014 	/*
1015 	 * Clear TID on mm_release()?
1016 	 */
1017 	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1018 
1019 	/*
1020 	 * Syscall tracing should be turned off in the child regardless
1021 	 * of CLONE_PTRACE.
1022 	 */
1023 	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1024 #ifdef TIF_SYSCALL_EMU
1025 	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1026 #endif
1027 
1028 	/* Our parent execution domain becomes current domain
1029 	   These must match for thread signalling to apply */
1030 
1031 	p->parent_exec_id = p->self_exec_id;
1032 
1033 	/* ok, now we should be set up.. */
1034 	p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1035 	p->pdeath_signal = 0;
1036 	p->exit_state = 0;
1037 
1038 	/*
1039 	 * Ok, make it visible to the rest of the system.
1040 	 * We dont wake it up yet.
1041 	 */
1042 	p->group_leader = p;
1043 	INIT_LIST_HEAD(&p->ptrace_children);
1044 	INIT_LIST_HEAD(&p->ptrace_list);
1045 
1046 	/* Perform scheduler related setup. Assign this task to a CPU. */
1047 	sched_fork(p, clone_flags);
1048 
1049 	/* Need tasklist lock for parent etc handling! */
1050 	write_lock_irq(&tasklist_lock);
1051 
1052 	/*
1053 	 * The task hasn't been attached yet, so its cpus_allowed mask will
1054 	 * not be changed, nor will its assigned CPU.
1055 	 *
1056 	 * The cpus_allowed mask of the parent may have changed after it was
1057 	 * copied first time - so re-copy it here, then check the child's CPU
1058 	 * to ensure it is on a valid CPU (and if not, just force it back to
1059 	 * parent's CPU). This avoids alot of nasty races.
1060 	 */
1061 	p->cpus_allowed = current->cpus_allowed;
1062 	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1063 			!cpu_online(task_cpu(p))))
1064 		set_task_cpu(p, smp_processor_id());
1065 
1066 	/*
1067 	 * Check for pending SIGKILL! The new thread should not be allowed
1068 	 * to slip out of an OOM kill. (or normal SIGKILL.)
1069 	 */
1070 	if (sigismember(&current->pending.signal, SIGKILL)) {
1071 		write_unlock_irq(&tasklist_lock);
1072 		retval = -EINTR;
1073 		goto bad_fork_cleanup_namespace;
1074 	}
1075 
1076 	/* CLONE_PARENT re-uses the old parent */
1077 	if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1078 		p->real_parent = current->real_parent;
1079 	else
1080 		p->real_parent = current;
1081 	p->parent = p->real_parent;
1082 
1083 	if (clone_flags & CLONE_THREAD) {
1084 		spin_lock(&current->sighand->siglock);
1085 		/*
1086 		 * Important: if an exit-all has been started then
1087 		 * do not create this new thread - the whole thread
1088 		 * group is supposed to exit anyway.
1089 		 */
1090 		if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1091 			spin_unlock(&current->sighand->siglock);
1092 			write_unlock_irq(&tasklist_lock);
1093 			retval = -EAGAIN;
1094 			goto bad_fork_cleanup_namespace;
1095 		}
1096 		p->group_leader = current->group_leader;
1097 
1098 		if (current->signal->group_stop_count > 0) {
1099 			/*
1100 			 * There is an all-stop in progress for the group.
1101 			 * We ourselves will stop as soon as we check signals.
1102 			 * Make the new thread part of that group stop too.
1103 			 */
1104 			current->signal->group_stop_count++;
1105 			set_tsk_thread_flag(p, TIF_SIGPENDING);
1106 		}
1107 
1108 		if (!cputime_eq(current->signal->it_virt_expires,
1109 				cputime_zero) ||
1110 		    !cputime_eq(current->signal->it_prof_expires,
1111 				cputime_zero) ||
1112 		    current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1113 		    !list_empty(&current->signal->cpu_timers[0]) ||
1114 		    !list_empty(&current->signal->cpu_timers[1]) ||
1115 		    !list_empty(&current->signal->cpu_timers[2])) {
1116 			/*
1117 			 * Have child wake up on its first tick to check
1118 			 * for process CPU timers.
1119 			 */
1120 			p->it_prof_expires = jiffies_to_cputime(1);
1121 		}
1122 
1123 		spin_unlock(&current->sighand->siglock);
1124 	}
1125 
1126 	/*
1127 	 * inherit ioprio
1128 	 */
1129 	p->ioprio = current->ioprio;
1130 
1131 	SET_LINKS(p);
1132 	if (unlikely(p->ptrace & PT_PTRACED))
1133 		__ptrace_link(p, current->parent);
1134 
1135 	cpuset_fork(p);
1136 
1137 	attach_pid(p, PIDTYPE_PID, p->pid);
1138 	attach_pid(p, PIDTYPE_TGID, p->tgid);
1139 	if (thread_group_leader(p)) {
1140 		attach_pid(p, PIDTYPE_PGID, process_group(p));
1141 		attach_pid(p, PIDTYPE_SID, p->signal->session);
1142 		if (p->pid)
1143 			__get_cpu_var(process_counts)++;
1144 	}
1145 
1146 	if (!current->signal->tty && p->signal->tty)
1147 		p->signal->tty = NULL;
1148 
1149 	nr_threads++;
1150 	total_forks++;
1151 	write_unlock_irq(&tasklist_lock);
1152 	retval = 0;
1153 
1154 fork_out:
1155 	if (retval)
1156 		return ERR_PTR(retval);
1157 	return p;
1158 
1159 bad_fork_cleanup_namespace:
1160 	exit_namespace(p);
1161 bad_fork_cleanup_keys:
1162 	exit_keys(p);
1163 bad_fork_cleanup_mm:
1164 	if (p->mm)
1165 		mmput(p->mm);
1166 bad_fork_cleanup_signal:
1167 	exit_signal(p);
1168 bad_fork_cleanup_sighand:
1169 	exit_sighand(p);
1170 bad_fork_cleanup_fs:
1171 	exit_fs(p); /* blocking */
1172 bad_fork_cleanup_files:
1173 	exit_files(p); /* blocking */
1174 bad_fork_cleanup_semundo:
1175 	exit_sem(p);
1176 bad_fork_cleanup_audit:
1177 	audit_free(p);
1178 bad_fork_cleanup_security:
1179 	security_task_free(p);
1180 bad_fork_cleanup_policy:
1181 #ifdef CONFIG_NUMA
1182 	mpol_free(p->mempolicy);
1183 #endif
1184 bad_fork_cleanup:
1185 	if (p->binfmt)
1186 		module_put(p->binfmt->module);
1187 bad_fork_cleanup_put_domain:
1188 	module_put(p->thread_info->exec_domain->module);
1189 bad_fork_cleanup_count:
1190 	put_group_info(p->group_info);
1191 	atomic_dec(&p->user->processes);
1192 	free_uid(p->user);
1193 bad_fork_free:
1194 	free_task(p);
1195 	goto fork_out;
1196 }
1197 
1198 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1199 {
1200 	memset(regs, 0, sizeof(struct pt_regs));
1201 	return regs;
1202 }
1203 
1204 task_t * __devinit fork_idle(int cpu)
1205 {
1206 	task_t *task;
1207 	struct pt_regs regs;
1208 
1209 	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
1210 	if (!task)
1211 		return ERR_PTR(-ENOMEM);
1212 	init_idle(task, cpu);
1213 	unhash_process(task);
1214 	return task;
1215 }
1216 
1217 static inline int fork_traceflag (unsigned clone_flags)
1218 {
1219 	if (clone_flags & CLONE_UNTRACED)
1220 		return 0;
1221 	else if (clone_flags & CLONE_VFORK) {
1222 		if (current->ptrace & PT_TRACE_VFORK)
1223 			return PTRACE_EVENT_VFORK;
1224 	} else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1225 		if (current->ptrace & PT_TRACE_CLONE)
1226 			return PTRACE_EVENT_CLONE;
1227 	} else if (current->ptrace & PT_TRACE_FORK)
1228 		return PTRACE_EVENT_FORK;
1229 
1230 	return 0;
1231 }
1232 
1233 /*
1234  *  Ok, this is the main fork-routine.
1235  *
1236  * It copies the process, and if successful kick-starts
1237  * it and waits for it to finish using the VM if required.
1238  */
1239 long do_fork(unsigned long clone_flags,
1240 	      unsigned long stack_start,
1241 	      struct pt_regs *regs,
1242 	      unsigned long stack_size,
1243 	      int __user *parent_tidptr,
1244 	      int __user *child_tidptr)
1245 {
1246 	struct task_struct *p;
1247 	int trace = 0;
1248 	long pid = alloc_pidmap();
1249 
1250 	if (pid < 0)
1251 		return -EAGAIN;
1252 	if (unlikely(current->ptrace)) {
1253 		trace = fork_traceflag (clone_flags);
1254 		if (trace)
1255 			clone_flags |= CLONE_PTRACE;
1256 	}
1257 
1258 	p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
1259 	/*
1260 	 * Do this prior waking up the new thread - the thread pointer
1261 	 * might get invalid after that point, if the thread exits quickly.
1262 	 */
1263 	if (!IS_ERR(p)) {
1264 		struct completion vfork;
1265 
1266 		if (clone_flags & CLONE_VFORK) {
1267 			p->vfork_done = &vfork;
1268 			init_completion(&vfork);
1269 		}
1270 
1271 		if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1272 			/*
1273 			 * We'll start up with an immediate SIGSTOP.
1274 			 */
1275 			sigaddset(&p->pending.signal, SIGSTOP);
1276 			set_tsk_thread_flag(p, TIF_SIGPENDING);
1277 		}
1278 
1279 		if (!(clone_flags & CLONE_STOPPED))
1280 			wake_up_new_task(p, clone_flags);
1281 		else
1282 			p->state = TASK_STOPPED;
1283 
1284 		if (unlikely (trace)) {
1285 			current->ptrace_message = pid;
1286 			ptrace_notify ((trace << 8) | SIGTRAP);
1287 		}
1288 
1289 		if (clone_flags & CLONE_VFORK) {
1290 			wait_for_completion(&vfork);
1291 			if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1292 				ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1293 		}
1294 	} else {
1295 		free_pidmap(pid);
1296 		pid = PTR_ERR(p);
1297 	}
1298 	return pid;
1299 }
1300 
1301 void __init proc_caches_init(void)
1302 {
1303 	sighand_cachep = kmem_cache_create("sighand_cache",
1304 			sizeof(struct sighand_struct), 0,
1305 			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1306 	signal_cachep = kmem_cache_create("signal_cache",
1307 			sizeof(struct signal_struct), 0,
1308 			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1309 	files_cachep = kmem_cache_create("files_cache",
1310 			sizeof(struct files_struct), 0,
1311 			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1312 	fs_cachep = kmem_cache_create("fs_cache",
1313 			sizeof(struct fs_struct), 0,
1314 			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1315 	vm_area_cachep = kmem_cache_create("vm_area_struct",
1316 			sizeof(struct vm_area_struct), 0,
1317 			SLAB_PANIC, NULL, NULL);
1318 	mm_cachep = kmem_cache_create("mm_struct",
1319 			sizeof(struct mm_struct), 0,
1320 			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1321 }
1322